JP2010517423A - Adaptive encoding and decoding method for video signal - Google Patents

Abstract

  A method for encoding a video signal includes an acquisition step, an averaging step, an offset step, and a replacement step. In the obtaining step, a first value including a video characteristic value for the first portion of the first video signal and a second value including a video characteristic value for the second portion of the second video signal are obtained. In the averaging step, the first value and the second value are averaged to obtain an average value. In the offset step, the average value is offset by a predetermined first offset value to obtain a first offset value, and the average value is offset by a predetermined second offset value to obtain a second offset value. In the replacement step, the first value is replaced with the first offset value in the first video signal, and the second value is replaced with the second offset value in the second video signal.

Description

  The present invention relates generally to encoding and decoding video signals including video content (video content) and control signals for display on a display screen. The present invention more particularly encodes information, for example a video signal including a display mode of the video signal on a display screen, such as a two-dimensional (2D) mode and a three-dimensional (3D) mode, and The present invention relates to decoding a display signal for displaying video content according to encoded information.

  Many video display devices for displaying video content are known in the art. The video content displayed on these conventional display devices generally consists of a plurality of video signals in a known or easily verifiable format. For example, NTSC video signals and MPEG-4 encoded video signals are standard video formats widely known in the art.

  Increasingly sophisticated display devices have improved the ability to display video content. For example, some display devices have become known as devices capable of displaying 3D images as well as 2D images. However, not all video content supplied to such a display device can be displayed in 3D, so in the art, in order to be able to switch the display device between 2D mode and 3D mode, There is a request that display mode information and other control information corresponding to the video content should be provided as information for informing the display device that the video content can be expressed in three dimensions.

  A method for providing such additional information to a display device has been filed on Sep. 7, 2006 and assigned to the same assignee as the present application, US patent application 11/470985 entitled “Personal Video Display Device”. Proposed in The disclosure content of that application is hereby incorporated by reference into this application.

  However, there remains a need in the art for additional methods of encoding video signals, more specifically video content, to provide display mode information to a video table. There is also a need in the art for a method of encoding a video signal having display mode information without noticeably degrading image quality. There is a further need for a method for decoding video content encoded with display mode information for a video display device.

  Encode and decode control information, such as display mode information, in the visible portion of the video signal to leave the control information available even when the video signal is converted from one format to another. There is also a need for a method.

  The present invention aims to answer the above-mentioned needs by providing a method for encoding and decoding display mode information and other information in the visible part of the video signal.

  According to one aspect of the invention, a method for decoding a video signal includes a first reading step, a second reading step, a comparing step, a determining step, and an acquiring step. In the first reading step, a first section of the video signal, for example a first line of the video signal, is read. In a second reading step, a corresponding second section of the video signal, for example a second line of the video signal, is read. In the comparing step, the second section corresponding to the first section is compared, and an output signal corresponding to the comparison result is generated. In the determining step, a difference between the first section and the second section is determined from the comparison result. The difference represents one data value. In the obtaining step, a plurality of data values in a number of video fields are obtained. The plurality of data values preferably include encoded instructions for displaying the video signal.

  According to a preferred embodiment of the present invention, the first section and the second section include portions of the first line and the second line of one video field, more preferably the first line of one video field. And a separate portion of the second line.

  According to another aspect of the invention, a method for encoding video content includes copying, determining, creating, and replacing. In the copying step, a portion of the first line of video content is copied. In the determining step, signal characteristic values are determined for the copied portion of the first line of video content. In the creating step, a signal portion is created for the copied portion of the first line of video content by adjusting the signal characteristics by at least a predetermined value. In the replacing step, a portion of the second line of video content corresponding to a portion of the first line of video content is replaced with the adjusted signal portion.

  According to a further aspect of the invention, a method for encoding a video signal includes obtaining, averaging, offsetting, and replacing. In the obtaining step, a first value including a video characteristic value for the first portion of the first video signal and a second value including a video characteristic value for the second portion of the second video signal are acquired. In the averaging step, the first value and the second value are averaged to obtain an average value. In the offset step, the first offset value is obtained by offsetting the average value by the first predetermined offset, and the second offset value is obtained by further offsetting the average value by the second predetermined offset. Is done. In the replacing step, the first value of the first video signal is replaced with the first offset value, and the second value of the second video signal is replaced with the second offset value.

  These and other features of the present invention will be understood by reference to the specification and drawings in which the invention is described or illustrated.

FIG. 2 is a diagram illustrating an overview of data transfer between a video source and a personal video display device according to an embodiment of the present invention. 5 is a flowchart illustrating an encoding method according to an exemplary embodiment of the present invention. 3 is a flowchart illustrating a decoding method according to a preferred embodiment of the present invention. 1 is a diagram showing an overview of a system according to a preferred embodiment of the present invention.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the general image display device 10 displays an image on a display screen 18 from video content supplied by a video source 60. The video content includes a plurality of video signals. The video signal is supplied in either an analog format or a digital format, and the image display device 10 includes a controller 66 and / or a processor 62 for displaying video content. The video signal includes interleaved video fields A and B to match a commonly adopted video format. When the combined video fields A and B are displayed on one display screen, the video fields A and B are A, B, A, B,... To display a two-dimensional video on the screen.・ Alternate playback. (As can be appreciated, the combination of combined fields A and B includes one frame, and a series of frames are played back in sequence to form a video. , B, and A are played back continuously, or A and B are played back continuously.)

  As an example, if the image displayed in FIG. 1 has a 320 × 240 region, the video consists of 240 lines, with each line having 320 pixels. Each of video fields A and B consists of 120 lines, and the combined video fields A and B consist of 240 lines. Each of the A fields consists of odd numbered lines (ie, lines 1, 3, 5... 237, 239), and each of the B fields consists of even numbered lines (ie, lines 0, 2, 4). ... 236, 238). Alternatively, the A field may be composed of even-numbered lines and the B field may be composed of odd-numbered lines. As is generally understood, each pixel constituting a line is a color sample having characteristics such as luminance, chrominance, hue, brightness, and coloring.

  As a standard format, video content including fields A and B may be provided to the display device as standard NTSC content. However, perhaps the NTSC analog signal is decoded into a YCrCb digital signal before being displayed on the display. Regardless of the format of the video signal, the present invention provides a method for encoding video content that incorporates information used to properly display the video content on a display device, for example.

  In a first preferred embodiment of the present invention, a method for encoding video content as described above includes changing the last two lines of a frame, namely lines 239 and 240. As shown in FIG. 2, the video signal is encoded with control information by changing the first 8 pixels of each of the last two lines of a frame (ie, the last line of each of fields A and B). The More particularly, as a preferred embodiment, one or more characteristics of each of the first 8 pixels of line 238 and one or more characteristics of each of the first 8 pixels of line 239 are encoded. In order to create a relationship between the signals, the control data is decoded from the relationship. For example, the first pixel of line 238 is changed so that one characteristic is intentionally larger or smaller than the same characteristic of the first pixel on line 239. For example, the luminance of the first pixel on line 238 is made larger or smaller than the luminance of the first pixel on line 239.

  The first 8 pixels of lines 238 and 239 are preferably changed in the same manner as the first pixel as described above. In particular, the second pixel of line 238 and the second pixel of 239 are preferably changed in the same manner as described above for the first pixel. The third, fourth, fifth, sixth, seventh and eighth pixels of each of lines 238 and 239 are similarly differentiated. Thus, 8 pixel pairs are provided between the two lines, each pixel pair having the same predetermined difference for one or more characteristics. As will become apparent from the description below, the difference in characteristics between each pixel pair is preferably substantially the same. Thus, in the first pixel pair, if the pixel characteristic of line 238 is greater than the characteristic of the corresponding pixel of line 239, the same characteristic of the second through eighth pixels of line 238 is also the corresponding individual of line 239. Should be larger than the pixel characteristics.

  The pixel pairs for the first 8 pixels of lines 238 and 239 are changed in a manner that can be read by the decoder as described above. In particular, as conceptually shown in FIG. 3, the decoder compares at least one pixel pair and determines from the comparison to determine whether the altered characteristic is large at line 238 or line 239. Get the data. In the preferred embodiment, a binary value of 1 is read by the decoder, for example, when the characteristics of one pixel in the first 8 pixels of line 238 are less than the same characteristics of the corresponding pixel of line 239. Conversely, when the characteristic of one pixel in the first 8 pixels of line 238 is greater than the same characteristic of the corresponding pixel of line 239, a binary value of 0 is determined. Thus, for each frame played by the digital video recorder, the decoder obtains either a binary value 1 or 0, which is a single bit, from the video signal. A data stream consisting of binary values 1 and 0 over a series of frames is obtained. This data stream may include some instructions for the video display device, along with additional identification information, error check information, and the like. The data stream may be arranged in a selected number of frames, but it is preferable to encode all frames of the video content as described above, so that, for example, the video is Even when starting from the position (midway), necessary information can be obtained continuously.

  Obviously, according to what has been described above, one pixel pair need only be considered by the decoder in order to determine the data bits for each frame. However, as described above, it is desirable that each of the first eight pixel pairs be changed while having the same relationship to each other. In particular, according to the inventor's knowledge, changing the 1st to 8th pixels in the same way eliminates the need for the decoder to select exactly one pixel from those pixels. As long as the decoder selects the same number of pixels on lines 239 and 238, it can obtain the required characteristic difference between the two lines, and the required data (characteristic difference) is the video signal. Is decrypted from. The decoder is only required to read some of the pixels from the 1st to the 8th and only need to read the same number of pixels from each line. In fact, according to the inventor's knowledge, in a typical display device, it is sometimes the case that the decoder accurately selects several pixels (eg, the first pixel, the tenth pixel, etc.) from one line. Have difficulty. However, when one pixel is selected from the first line, it is relatively easy to select the same number of pixels in the second line. Therefore, the decoder does not need to know which pixel from the first to the eighth is selected, and simply selects one pixel within that range.

  As described above, one or more of a number of video characteristics are modified to obtain the desired characteristic difference between pixels in adjacent lines 238 and 239. That is, many different characteristic changes are differences that the decoder can read and recognize. These characteristics include brightness, chrominance, coloring, brightness, hue, and the like. Of course, by changing any of these characteristics for each of the 8 pixels on lines 238 and 239, the image displayed by the display device is necessarily changed. As an extreme example, the decoder detects a binary “1” when the pixel on line 238 is white and the corresponding pixel on line 239 is black, and the pixel on line 238 is black and the corresponding pixel on line 239 is If it is decided to detect binary "0" when white, each frame contains a thin strip of two lines 8 pixels wide. There is a white strip on the black strip or a black strip on the white strip. As a preferred example, when a series of frames are encoded to provide a data stream to the decoder, the strip is visible to the human eye. More preferably, the encoding is performed over the entire video content, where the video content may start from the beginning or midway, but the video display device can obtain information conveyed by the data, and the thin strip is Visible throughout the video.

  Most likely, two adjacent lines have very similar characteristics. This occurs, for example, when a display portion that includes two adjacent lines displays similar objects or the same object. However, in some situations, adjacent lines may have completely different characteristics. For example, when a horizontal line running on an adjacent line is displayed.

  The present invention is characterized by an adaptive encoding technique that minimizes the visibility of encoding by a normal observer (viewer). The technique will be described with reference to FIG. As shown in FIG. 2, when the brightness is a property to be changed (and later decoded by the decoder), the brightness of the first pixel on lines 238 and 239 is determined. Using the brightness difference, an average brightness value N for the pixel pair is determined. Lines 238 and 239 are then coded such that the first pixel of lines 238 and 239 has a lightness value equal to a value offset (shifted) from its average lightness value N by a predetermined lightness offset n. It becomes. Preferably, the pixels on lines 238 and 239 are offset together. That is, one is offset in the negative direction (the pixel is dark by a predetermined lightness offset n) and the other is offset in the positive direction (the pixel is lighter by a predetermined lightness offset n), thereby reducing the total offset by 2n. Will give. According to the preferred embodiment described above, when a pixel pair represents a binary “1”, the pixels in line 238 are brightened by offsetting the average brightness value N plus a predetermined brightness offset n, and the pixels in line 239 are By subtracting a predetermined lightness offset n from the average lightness value N, it is required to be relatively dark. Similarly, when a pixel pair represents a binary “0”, the pixel on line 239 is made relatively brighter than the corresponding pixel on line 238. Of course, the corresponding pixel arrangement is swapped in the same way when the encoder swaps binary “1” and “0”.

  The operations described above for the pixel pairs located on lines 238 and 239 are performed for each of the first eight pixels on lines 238 and 239, as described above. The inventor has found that by averaging each pixel pair and offsetting a constant offset n from the average, the degradation in image quality caused by brightness changes is minimized. It is also possible to obtain an average of 8 pixels on line 238 and an average of 8 pixels on line 239 and further average these to determine an average value N. Of course, this allows all 8 pixels on line 238 to have the same brightness value and all 8 pixels on line 239 to have the same brightness value offset with respect to the pixels on line 238. Groups of two or more pixels can be changed as well.

  As will be appreciated by those skilled in the art, the smaller the constant offset n, the less image quality degradation that can be seen. However, according to the inventor's knowledge, the offset should be at least a minimum offset that can ensure an appropriate difference between pixels that form a pixel pair when decoding. In particular, according to the inventor's knowledge, an offset n of approximately 16 to 24 tones in a scale from 0 to 255 is sufficient for the decoder to identify the proper difference between pixels. Provide (margin).

  Other ways of offsetting the pixels to obtain the desired difference between the pixels are conceivable. For example, instead of taking the average of each pixel pair and offsetting it from that average for each pixel, use this average brightness value N as either one of the brighter or darker pixels and the other pixel to this average brightness value. On the other hand, it is offset upward or downward. Further, as an alternative configuration, the encoder can determine the characteristics of the pixels in line 238 and offset the same characteristics of the corresponding pixels in line 239 up or down to achieve similar results. Of course, similar results can be obtained by offsetting the characteristic values of line 238 relative to line 239 while leaving the pixels of line 238 unchanged. In this way, only one line of information needs to be offset and no averaging is required. For example, this offset method is particularly useful when pixels are at or near the upper or lower limits. More specifically, in an example where both pixels are black, neither of those pixels can be darker. Instead, it does not change that one pixel and offsets the other pixel by some identifiable amount.

  According to the encoding method described in this regard, the digital signal is preferably one pixel or group of pixels in the first line of the first field and one corresponding pixel or pixel in the adjacent second line of the second field. Encoded to create a recognizable difference between pixels. As a variant, however, the video signal is encoded to show a recognizable difference in multiple lines of the same field, such as lines 237 and 239 or lines 236 and 238. The difference is preferably made in the same way as described above.

  As a result of any of the video content encoding methods described above, the digital signal displayed on the two lines of the video display will differ between the pixels on the first line and the corresponding pixels on the second line. Are encoded as follows. Preferably, the difference is decoded by the decoder to represent either binary “0” or “1”. Thus, if adjacent lines of successive fields are encoded as described above, each frame of video content is decoded by the decoder as representing either binary “0” or “1” and a series of A data stream is obtained from the frames. Similarly, if two lines of the same field are encoded as described above, each field of the video content is decoded by the decoder to represent either binary “0” or “1” and a series of A field provides a data stream. Alternatively, if each field represents either binary “1” or “0”, two data streams are obtained. For example, a data stream consisting of the value of the A field and a data stream consisting of the value of the B field are obtained. These data streams preferably inform the decoder of any of a number of information. For example, the information instructs the display device to display the image in a two-dimensional format or a three-dimensional format. Further, the three-dimensional format may be a regular three-dimensional format or a reverse three-dimensional format. Other information including, but not limited to, format information (eg, 4: 3 or 16: 9 magnification, letterbox, etc.), brightness information, contrast information and / or video display information may be used instead of the above information. Alternatively, it can be included in the data stream as an addition.

  As should be appreciated, the data stream is processed to output a set of binary codes, for example by processing the characteristics of the pixels in a series of frames or fields. However, since the decoder is reading a portion of the first 8 pixels of the two lines, if there is unencoded content, the decoder will show a difference, for example a brightness difference between the corresponding pixels of the two lines. There is a possibility of reading. This also gives rise to the following possibilities. That is, information such that the unencoded video content displayed by the video display device is understood by the decoder as information related to the display of the video content is randomly generated. This will be described in more detail. First, assume that the data stream “0, 1, 0, 1, 0, 1” indicates that the video content should be displayed in three dimensions on the display device. If the content is not encoded and the decoder happens to acquire a data stream as described above from 6 consecutive frames (or fields), the content is not formatted as a 3D display, The display device will try to display the content in three dimensions.

  The present invention provides a recognizable and authentic bit pattern that is unlikely to be found by chance. In particular, the data stream according to the invention preferably comprises an 8-bit start sequence and an 8-bit stop sequence, between which information to be transmitted to the display device is encoded. Thus, only when recognizing both start and stop sequences, the decoder looks for data following the start signal, and when that data continues to the predetermined stop signal, the encoded data is recognized and the display device is set. Will be used to do. In the preferred embodiment, the start sequence is hex 9, x9 followed by hex 6, x6, and the stop sequence is x6 followed by x9. For example, as shown in FIGS. 2 and 3, the information of the first 8 bits (start sequence) including the data stream is “1, 0, 0, 1, 0, 1, 1, 0”, and the last The 8-bit (stop sequence) data stream is “0, 1, 1, 0, 1, 0, 0, 1”. The information included in the start sequence and the stop sequence may be any number of bits. In FIG. 2 (FIG. 3), 8 bits are used for illustrative purposes only. Further, the start and stop bit patterns can be any pattern as will be understood by those skilled in the art.

  According to a preferred embodiment, the complete data stream consists of 24 bits of information including start and stop sequences and information between them. If each bit corresponds to one frame of video content, for example if lines 238 and 239 are changed to make the desired difference, information relating to the display of the video signal in less than 0.5 seconds from the start of the start sequence Can be recognized (assuming that the video content is displayed at 60 frames per second). If the two lines in each field are modified to create a recognizable difference, information related to the display of the video signal may be recognized in a shorter time. Thus, adjustments made to the video that result from interpreting the acquired information can be quickly implemented. This is particularly useful when the information relates to a method or mode for displaying video content. If the video is displayed in 3D, for example, the video display device will realize the 3D display in a very short time and the video viewing by the user will not be interrupted. Although shorter data streams allow for faster information recognition, this data stream is more likely to occur accidentally. In contrast, longer data streams can be used to reduce the chance of accidental occurrences, but this prolongs information recognition.

  FIG. 4 shows a computer system using the above-described encoding and decoding system (method). As shown in FIG. 4, a pre-encoded analog video signal is input to an NTSC decoder. The NTSC decoder decodes the analog video signal and outputs YCrCb digital video data. This digital data carries previously encoded information as described above and is input to a complex programmable logic device (CPLD). The CPLD takes the information encoded from the video signal in the manner described above and provides a digital data stream to the microcontroller. The microcontroller decodes the information carried by the data stream to change the display of the video signal. As an example, the microcontroller instructs the display device to display the video signal in two, three or reverse three dimensions.

A typical decoding algorithm used by CPLD is shown below.

A typical software routine for decoding information received by the microcontroller from the CPLD is shown below.

  Although a preferred embodiment of the present invention has been described with reference to a 320 × 240 region, the present invention includes any size region, including but not limited to a 640 × 240 or 640 × 480 region. . Furthermore, although the present invention has been described as processing the last two lines of pixels of a frame, any line can be used. Further, the two lines may be adjacent to each other like lines 238 and 239 or may be spaced apart.

  Although the first 8 pixels have been described as processed pixels in the preferred embodiment, it can be changed to more or less than 8 pixels. In addition, the pixel may be a pixel anywhere along the line, not the first 8 pixels of the line. The location of the changed pixels in the preferred embodiment is generally selected to be in the periphery of the display area, ie where the perceptible changes will be as inconspicuous as possible to the viewer. More or less than 8 pixels may be processed to achieve the objectives of the present invention.

  Although the present invention has been described as providing a difference between corresponding pixels in two lines, more than one line may be encoded. For example, an average value N for certain characteristics of the corresponding pixels in lines 237, 238 and 239 may be obtained. In this example, the characteristics of the pixels on line 238 are set to match the average value N, and the same characteristics of the corresponding pixels on line 237 are offset by adding or subtracting an offset n from the average value N. Then, by subtracting or adding and offsetting the same characteristic of the corresponding pixel in line 239, binary “1” or “0” can be represented. As will be appreciated, certainty (decoding) at the decoder improves when more lines are used and more comparisons are made. However, if more lines are affected, the likelihood of the encoding being perceived by the viewer watching the video content is also greater.

  As described above, two lines of the same or consecutive fields provide one data bit for one data stream. In a variant, the additional pixels are encoded according to the invention so as to give more than one data bit per frame or field. For example, as described above, binary “1” or “0” is determined from lines 238 and 239, and the other two lines (eg, lines 1 and 2) are encoded to include other information elements. That is, for example, another binary “1” or “0” is used in another data stream. In this way, additional information is transmitted in a relatively short time.

  In other embodiments of the present invention, the start and stop sequences described above to reduce the chance of accidental data streams are altered. In particular, a periodic redundancy check is additionally used or substituted for one or both of the start and stop sequences. For example, the stop sequence is replaced with an 8-bit periodic redundancy check. Such an arrangement has been found to help reduce the misinterpretation (misinterpreted as a true signal) caused by using the arrangement described above.

The above-described embodiments are exemplary embodiments and have been described for purposes of illustration. The embodiments do not limit the scope of the invention. Changes and modifications will become apparent from reading the above description and are included within the scope of the invention. The invention is limited only by the claims.

Claims (23)

A method of decoding a video signal,
Reading a first section of a first line of a video signal, a first reading step;
Reading a corresponding section of the second line of the video signal, a second reading step;
Comparing the first section of the first line and the corresponding second section of the second line;
Determining a difference between the first section and the second section from the comparison, the difference representing a data value;
Obtaining a plurality of data values in a number of video fields, wherein the plurality of data values includes instructions for displaying a video signal;
Including methods.   The method of claim 1, wherein the first section comprises a number of pixels.   The method of claim 2, wherein the second section comprises a number of pixels.   The method of claim 3, wherein the first line and the second line are adjacent lines.   The method of claim 1, wherein the first line and the second line are pixel columns displayed on a display device. A method for encoding video content comprising:
(A) copying a portion of the first line of video content;
(B) determining a signal characteristic value for a copied portion of the first line of video content;
(C) for the copied portion of the first line of video content, adjusting the signal characteristic value by at least a predetermined value to create an adjusted signal portion;
(D) replacing a portion of the second line of video content corresponding to a portion of the first line of video content with the adjusted signal portion;
Including a method.   The method of claim 6, wherein a portion of the first line of video content comprises 8 to 24 pixels.   The method of claim 6, wherein the signal characteristic is one of luminance, chrominance, coloring, hue, or brightness.   The method of claim 8, wherein the signal characteristic is increased by at least a predetermined value to indicate a binary “0” or “1” and decreased by at least a predetermined value to indicate another binary “0” or “1”.   The method of claim 6, wherein the first line of video content and the second line of video content are adjacent horizontal lines in the same frame.   The method of claim 6, wherein the first line of video content is included in a first field and the second line of video content is included in a second field. The first line and the second line are displayed in a first frame, and the adjusted signal portion provides a difference in signal characteristics between the first line and the second line. 7. The method of claim 6, comprising:
(E) Steps (a) to (d) are performed a plurality of times to provide a difference in signal characteristics for each of a plurality of consecutive frames. The difference between the signal characteristics in the plurality of consecutive frames can be read to form a data stream.   The method of claim 12, wherein the difference in signal characteristics is readable as a binary value and the data stream comprises a series of binary values.   The method of claim 12, wherein the data stream includes information related to the video content.   15. The method of claim 14, wherein the data stream includes information relating to whether the video content is displayed as 2D video content or 3D video content. A method for encoding a video signal, comprising:
(A) obtaining a first value including a video characteristic value for a first portion of the first video signal and a second value including a video characteristic value for a second portion of the second video signal;
(B) averaging the first value and the second value to obtain an average value;
(C) offsetting the average value by a predetermined first offset to obtain a first offset value, offsetting the average value by a predetermined second offset to obtain a second offset value;
(D) replacing the first value of the first video signal with a first offset value and replacing the second value of the second video signal with a second offset value;
Including a method.   17. The first portion of the first video signal is pixels on a first line of video content, and the second portion of the second video signal is pixels on a second line of video content. Method   The method of claim 16, wherein the video characteristic is one of luminance, chrominance, coloring, hue, or brightness.   The first video signal includes a first field, the second video signal includes a second field, the first field and the second field include one frame, and the steps (a) to (d) are performed. The method of claim 16, wherein the steps are performed in a plurality of frames displayed in succession.   The method of claim 19, wherein a difference between the first offset value and the second offset value represents one data value, and one data string is encoded in a plurality of frames. It is a method of encoding control information in the visible part of the video signal.
Determining a value of a selected first viewable portion of the video signal;
Determining a value of a selected second viewable portion of the video signal;
Determining a value of control information encoded in the video signal;
Adjusting the difference between the value of the selected first viewable portion and the value of the selected second viewable portion according to the value of the control information;
Including a method.   Determining the value of the selected first viewable portion includes determining the value of the selected portion of the first line of the video signal, the selected second viewable portion. The method of claim 21, wherein determining the value of comprises: determining a value of a selected portion of the second line of the video signal. Adjusting the difference between the value of the selected first viewable portion and the value of the selected second viewable portion according to the value of the control information is selected for the first line. 23. The method of claim 22, comprising adjusting a value of a portion and copying to a selected portion of the second line.

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